JONATHAN FRUIT-SPOT. 



13 



bility. It has also been observed to a very slight extent on the 

 Grimes, Arkansas Black, and a few other varieties of less importance. 

 Dry weather during the summer is apparently favorable to the de- 

 velopment of the Jonathan fruit-spot. It was very bad in 1910 and 

 1911, both of which were dry seasons, while in 1912, a comparatively 

 wet season, it was not common on eastern-grown fruit. In the fall 

 of 1911 the spotting was particularly serious on the Jonathan, speci- 

 mens having been received from practically every section of the 

 country where that variety is grown. 



Fig. 2.— Esopus (Spitzenbcrg) apple showing older stages of the Jonathan fruit-spot. 



SPRAYING AND STORING EXPERIMENTS. 



In order to test the supposition that the Jonathan fruit-spot 

 might be due to arsenical injury, spraying experiments were con- 

 ducted in the orchard of Mr. S. H. Derby, at Woodside, Del., during 

 1911. A block of Jonathan apple trees about 15 years old was 

 divided into 5 plats of 6 trees each and treated as follows : 



Commercial lime-sulphur solution at the rate of 1} gallons to each 50 gallons of 



water was used in connection with arsenate of lead on all of the sprayed plats. The 



amouDt of arsenate of lead was varied from one-half pound to 5 pounds in each 50 



gallons of spray. Plat I was sprayed with one-half pound, Plat II with 1 pound, 



[Cir. 112] 



